Along with a rapid development of display technology, an organic light emitting diode (OLED) is gradually taking place of a traditional liquid crystal display. The OLED display technology has many outstanding merits such as self-illumination, low-energy consumption, high contrast, wide-angle view, being available for flexible displaying, etc. As a result, OLED with great development potential is considered to be a next generation display technology, a replacement for the liquid crystal display.
Despite the rapid development, the OLED display technology still has many problems which need to be solved, including that it is difficult to detect an OLED-panel encapsulation effect, detecting sensitivity is low, and it is difficult to determine a defect position, etc. An OLED device usually uses a sandwich structure. An organic light-emitting layer is sandwiched between two electrodes on its both sides, and a hole and an electron are respectively injected into an anode and a cathode. The hole and electron are transported in the organic light-emitting layer, and meet to form an exciton. And then light is emitted due to exciton recombination. The organic light-emitting layer is easy to react with water vapor. A compound produced by the reaction significantly reduces quantum efficiency of the OLED device. Hence, an encapsulation level of the OLED panel directly impacts reliability and service life of the OELD device. The detection of the OLED panel encapsulation effect and the determination of the defect position of the encapsulation are of great importance to improve yield of the OLED panel and reduce cost. There are very few detecting techniques for an encapsulation structure of the OLED panel in the related art. Usually, professional equipment needs to be used for detecting water vapor content, or an addition structure for detecting water vapor is added in the encapsulation structure which increases process complexity.
In the encapsulation structure, there is often residue or foreign matter on a contact surface between an encapsulating adhesive and glass, resulting in an imperfect fit. There may also be a defect when a thin film encapsulation layer is coated in vacuum, or foreign matter on a surface of thin film encapsulation layer may also result in that the thin film encapsulation layer is coated imperfectly. In addition, usually, a thermal curing process on the encapsulation adhesive is needed in the related art, and it is easy to create an opening on the encapsulation adhesive in the thermal curing process. The water vapor may enter in through these defects, most of which are in nanoscale, thus reducing the reliability and service life of the OELD device. It is difficult to detect these nano-scaled defects by a detecting device in a current production line, or a complex detecting method is needed.